Comparison of Surface Roughness of Zirconia Polished with Novel Silicon Carbide Polishing Paste and Diamond Polishing Paste

The aim of this study was to newly develop a silicon carbide polishing paste that was comparable to or more effective than diamond polishing paste for the final polishing step of zirconia.Fifty-two zirconia specimens were prepared, and polished with silicon carbide sandpaper to generate initial surface roughness. The surface roughness at baseline (Ra value) was measured by a profilometer and the specimens were randomly divided into six groups, which the first group (<i>n</i> = 2) was used to study the surface morphology at baseline. The second to fifth groups (<i>n</i> = 10/group) were polished for 30 seconds with different ratios of silicon carbide paste; silicon carbide:glycerin by weight: 1:1 (SiC1), 1.5:1 (SiC1.5), 2:1 (SiC2), and 2.5:1 (SiC2.5) according to their groups. The sixth group (<i>n</i> = 10) was polished for 30 seconds with diamond paste (Dia). Afterward, the Ra values were remeasured at every 30-second polishing interval up to a total polishing time of 120 seconds. Scanning electron microscopy (SEM) was used to examine the surface morphology of postpolished specimens and the abrasive particles.The differences in mean Ra values were analyzed using two-way repeated analysis of variance followed by least significant difference post hoc analysis. All tests were conducted at a significance level of 5% (<i>p</i> < 0.05).Within each group, the mean Ra values significantly decreased with longer polishing time (<i>p</i> < 0.05), except the SiC2.5 group at 120 seconds. Increasing silicon carbide concentration significantly decreased the Ra values (<i>p</i> < 0.05), with the exception of the SiC2.5 group. After 120 seconds, the SiC2 group demonstrated the lowest mean Ra value. The surface images investigated by SEM corresponded with their Ra values.Polishing zirconia with a silicon carbide paste, silicon carbide:glycerin ratio of 2:1 by weight, for 120 seconds, yields the smoothest postpolished surface. Furthermore, the mean Ra value obtained with this paste is statistically comparable to that of the diamond paste. Thus, silicon carbide paste has the potential to be an efficient alternative to diamond paste for chairside polishing of zirconia.